Priority is claimed from patent application No. 99/09908 filed in France on Jul. 30, 1999.
The present invention relates to a method and a device for cleaning containment enclosures, in particular for dedusting them.
In various industries, and in particular in the nuclear industry, there exist containment enclosures which enclose hazardous materials, so that it is essential to ensure the atmosphere remains confined. Various manipulations are performed during which it is essential to protect the people performing the manipulations within such enclosures. The enclosures are generally provided with at least one standard opening that is designed in particular for transferring contaminated materials, tools, and various kinds of waste. Such enclosures are often maintained at a pressure below ambient and they are always ventilated. In spite of such ventilation, they generally become polluted in use by solids (in particular powders) and/or by liquids, and this can happen progressively or suddenly, e.g. in the event of an exceptional operation. It then becomes necessary to evacuate such solids and/or liquids from said enclosures.
To implement such evacuation without breaking containment, a first variant of the practice recommended and/or used at present is as follows: known, relatively complex and expensive suction devices are secured to said enclosures; such enclosure is thus from the beginning and throughout its use fitted with such a suction device a second variant is as follows: suction devices are inserted inside said enclosures and they remain therein, so that in the long run they end up themselves as constituting waste to be evacuated and treated.
According to the invention, it has been found that it is possible to make such operations of cleaning containment enclosures much more flexible by making use of a removable suction device, and that this can be done while always maintaining double containment.
The method and the device of the invention have been designed on these lines.
In a first aspect, the present invention thus provides a method of dedusting a containment enclosure provided with at least one standard opening closed by a retractable closure device with appropriate suction means. In this respect, the method of the invention is of the same type as prior art cleaning methods. In a manner characteristic of the method of the invention, the suction means operates in a removable receptacle suitable for docking on and for undocking from said standard opening of said containment enclosure.
According to the invention, a removable suction device (constituted by suction means arranged in a suitable receptacle) is used that is suitable for docking on and for undocking from at least one of the standard openings, while maintaining double containment. A single device of this type can be used for cleaning a plurality of enclosures. Such a device can itself be cleaned in a suitable station between two successive uses.
The method of the invention is advantageously implemented using the double-door sealed transfer technique familiar to the person skilled in the art, and comprises:
taking a receptacle closed by a retractable cover having an outside face and temporarily docking it in a leakproof maimer onto a closed standard opening having an outside face with dimensions substantially the same as those of the retractable cover, the receptacle being docked by aligning the outside face of the cover with the outside face of the receptacle, the outside faces of the cover and of the standard opening thus coming into contact, the receptacle also including suitable suction means having a free suction endpiece closed by a removable plug;
securing the cover of the docked receptacle to the closure device of the standard opening so as to constitute an assembly;
retracting the assembly into the inside of the containment enclosure so as to put the inside of the enclosure into communication with the inside of the docked receptacle;
retracting the removable plug so as to release the free suction endpiece of the suction means;
establishing suction by actuating the suction means, and subsequently stopping the suction by deactuating said means;
closing the free suction endpiece by means of the plug;
closing in leakproof manner both the enclosure and the receptacle by putting the assembly back into place and separating the cover and the closure device making up the assembly; and
undocking the closed receptacle from the closed standard opening.
In general, in order to implement the method of the invention, it is naturally necessary to have available an appropriate removable suction device, and in particular one which is easily transported and handled (manually or using appropriate machinery).
In a second aspect, the present invention provides such a device. In characteristic manner, it comprises suction means including a free suction endpiece closed by a removable plug, and contained in a receptacle having a closed end wall and a front face provided both with means enabling it to be docked temporarily and in leakproof manner on a standard opening of a containment enclosure closed by a retractable closure device, and with a retractable cover suitable for being secured to the retractable closure device of the enclosure, the retractable cover and the retractable closure device having outside faces of the same size in contact with each others.
The device thus includes the means which act in succession to perform both static double containment and combined static and dynamic double containment.
In a variant that is particularly preferred for dedusting, the suction means are disposed within said removable receptacle and extending from its front face towards its end wall:
a suction tube whose free endpiece is closed by a removable plug;
an impact filter into which the suction tube opens out and beneath which there is placed a collector pot;
a filter stage for filtering the atmosphere coming from the containment enclosure via the impact filter; and
a suction turbine sucking in the atmosphere coming from said containment enclosure via said impact filter and the filter stage, and expelling it into the inside of the receptacle. While cleaning is taking place, the turbine is responsible for sucking in a polluted atmosphere and recycling the atmosphere once xe2x80x9cunpollutedxe2x80x9d into the receptacle and then back into the enclosure. The return flow of the xe2x80x9cunpollutedxe2x80x9d atmosphere from the receptacle to the enclosure prevents polluted atmosphere entering the receptacle from said enclosure.
The suction means advantageously further comprise a hose suitable for being secured to the free endpiece of the suction tube and suitable for penetrating into the inside of the enclosure to be cleaned. As stated above, such a hose can be provided inside the removable receptacle or inside the enclosure.
Whatever the variant concerned, the suction means are advantageously arranged inside the receptacle on a slider device. Such an arrangement enables the suction means to be extracted conveniently from said receptacle for cleaning purposes.